Electricity Invercargill is calling on the Commerce Commission to review how it calculates compliance after it received a warning for failing to comply with quality standards.

The commission sets quality standards every five years to ensure there is no decline in the reliability of service delivered to consumers by electricity distributors.

The quality standards limit the number and length of interruptions to the supply of electricity that a distributor is allowed in a given year.

Electricity Invercargill was among three electricity distributors the commission warned for failure in 2012 - the others were Aurora Energy Ltd, which covers Dunedin and Central Otago, and Eastland's electricity distribution network area that covers the East Cape and Northern Hawke's Bay.

PowerNet chief executive Jason Franklin said the incident related to an outage in January 2012, which was the result of a cable fault in the Windsor area.

It had taken the commission some time to decide if it would take action and Electricity Invercargill bosses were comforted it resulted in a warning and not an investigation.

Electricity Invercargill, which is managed by PowerNet, was one of the most reliable services in New Zealand so limits of operation were lower, he said.

"Because our limit is so low, it does not take much to push us over it . . . we do not get any real relief." The company had taken the breach seriously but there were issues about the way the commission measured its limits, he said.

It did not want to be penalised and the issue of "anomalies" surrounding the reliability of measuring limits had been raised.

It had now engaged with the commission regarding its calculations for the 2015-2020 period.

An asset management plan at Electricity Invercargill would continue to enhance and improve the network service, he said.

Commerce Commission deputy chairwoman Sue Begg said no serious fault on the part of the distributors was found and it considered the warnings to be enough to deter those companies - and other electricity distribution companies - from failing to comply with the quality standards again.

Electricity Invercargill provided evidence that its non-compliance came from three outages caused by isolated operational incidents, so an engineering review of Electricity Invercargill's network was unnecessary.

"Following their non-compliance, we have already seen the businesses take positive steps towards ensuring the level of service they deliver to customers in future meets the required standards.

"Eastland, Aurora and Electricity Invercargill are now on notice that they are more likely to face penalties should they fail to comply with the quality standards in the future. We expect them to take appropriate steps to mitigate the risk of failing to comply with quality standards again," Begg said.